1. Technical Field
The present invention relates in general to improved processing of individual disk drive sliders and, in particular, to an improved system, method, and apparatus for handling and testing individual ones of the sliders in single slider processing systems.
2. Description of the Related Art
Magnetic recording is employed for large memory capacity requirements in high speed data processing systems. For example, in magnetic disk drive systems, data is read from and written to magnetic recording media utilizing magnetic transducers commonly referred to as magnetic heads. Typically, one or more magnetic recording disks are mounted on a spindle such that the disk can rotate to permit the magnetic head mounted on a moveable arm in position closely adjacent to the disk surface to read or write information thereon.
During operation of the disk drive system, an actuator mechanism moves the magnetic transducer to a desired radial position on the surface of the rotating disk where the head electromagnetically reads or writes data. Usually the head is integrally mounted in a carrier or support referred to as a “slider.” A slider generally serves to mechanically support the head and any electrical connections between the head and the rest of the disk drive system. The slider is aerodynamically shaped to slide over moving air and therefore to maintain a uniform distance from the surface of the rotating disk thereby preventing the head from undesirably contacting the disk.
Typically, a slider is formed with essentially planar areas surrounded by recessed areas etched back from the original surface. The surface of the planar areas that glide over the disk surface during operation is known as the air bearing surface (ABS). Large numbers of sliders are fabricated from a single wafer having rows of the magnetic transducers deposited simultaneously on the wafer surface using semiconductor-type process methods.
After deposition of the heads is complete, single-row bars are sliced from the wafer, each bar comprising a row of units which can be further processed into sliders having one or more magnetic transducers on their end faces. Each row bar is bonded to a fixture or tool where the bar is processed and then further diced, i.e., separated into sliders having one or more magnetic transducers on their end faces. Each row bar is bonded to a fixture or tool where the bar is processed and then further diced, i.e., separated into individual sliders each slider having at least one magnetic head terminating at the slider ABS.
The slider head is typically an inductive electromagnetic device including magnetic pole pieces which read the data from or write the data onto the recording media surface. In other applications the magnetic head may include a magneto resistive read element for separately reading the recorded data with the inductive heads serving only to write the data. In either application, the various elements terminate on the ABS and function to electromagnetically interact with the data contained on the magnetic recording disk.
In order to increase the efficiency of the magnetic heads, the sensing elements must have precision dimensional relationships to each other as well as the application of the slider ABS to the magnetic recording disk. Each head has a polished ABS with flatness parameters, such as crown, camber, and twist. The ABS allows the head to “fly” above the surface of its respective spinning disk. In order to achieve the desired fly height, fly height variance, take-off speed, and other aerodynamic characteristics, the flatness parameters of the ABS need to be tightly controlled.
For component level testing, it is considerably easier to test the entire row of sliders for the following reasons: (1) it is much easier to handle rows rather than the individual sliders because of their physical dimensions; (2) it is less likely to damage (e.g., mechanical and electrostatic discharge) sliders on rows from handling; (3) the fixture requirements for placing the rows onto the tester are less stringent; (4) probing alignment on rows is much easier to do than on individual sliders because (a) the pitch distance between the sliders on rows is essentially fixed, and (b) the height of one slider relative to the others is essentially identical and miss-probing is less likely to occur. However, the yield on a single row may be quite poor. For low yield rows, the throughput for testing is low and testing more rows to increase sample size for obtaining statistical meaningful data is required, i.e., longer test time, which can impact product monitoring or design evaluation significantly. For slider-level component testing, one only places good sliders for measurements. In addition, today the trend is moving toward single slider lapping. Since component level testing is only meaningful on lapped devices, there may be no more row-level component testing in the future.